The definition of “mortal” is a state or condition of being liable to death, not a condition where death is unavoidable, but a condition where death is a possibility. The definition of “immortal” is a state or condition not liable to death, not merely freedom from death, but a condition where death is an impossibility.

The common, but erroneous idea of “mortal,” is a state or condition in which death is unavoidable.  It is this false idea of mortal that leads people in general to conclude that all beings that do not die are immortal.  Under this heading are classed Jehovah, Jesus, angels, and all who are saved of mankind.  We believe that this thinking is an error; that the great mass of mankind, once they are restored on earth, as well as angels in heaven will always be mortal.  Their condition for everlasting life either in heaven or on earth is and always will be obedience to God’s laws.

Nowhere in Scripture is it stated that angels are immortal, nor that humankind, once restored to perfection on earth in the next age, will be immortal. Immortality is ascribed only to the Divine Nature (to Jehovah, to Jesus in his present glorified condition, and to the Church, which is composed of faithful Christians known as the “little flock,” [Luke 12:32] the “Lamb’s wife” [Revelation 21:9] and “joint-heirs” [Romans 8:17]).

Not only do we have evidence that angels are not immortal, but we have scriptural proof that they are mortal. They can be destroyed. Here is what Hebrews 2:14 says about Satan’s fate. “So that by his death (Jesus’ death) he might destroy him who holds power of death—that is, the devil.”  If Satan, the most powerful of all the “fallen” angels is mortal and will be destroyed, then certainly those angels that left heaven to be with him are mortal as well and subject to judgment on the last day.  Their judgment will either be life or death. “And the angels who did not keep their positions of authority but abandoned their own home—these he kept in darkness, bound with everlasting chains for judgment on the great Day.” (Jude 7) The great Day is Judgment Day when the Church or “little flock,” now immortal saints, mentioned above, will do the judging.  “Do you not know that the saints will judge the world? . . . Do you not know that we will judge angels?” (1 Corinthians 6:3).

Are angels mortal? Yes, all angels, whether with God in heaven or with Satan now, are mortal, meaning that they are liable to the possibility of death.